1. Field of the Invention
The present invention relates to a method and apparatus by which sheet material is subjected to a predetermined processing, and an image recording apparatus.
2. Description of the Related Art
Generally, a photosensitive printing plate (hereinafter referred to as a xe2x80x9cprinting platexe2x80x9d), in which a photosensitive layer is formed on a support formed in a sheet configuration such as a thin aluminium plate, is utilized in printing. The printing plate is used as a printing plate for printing when development processing and the like is effected after an image has been recorded by exposure.
In such an image exposure apparatus in which a printing plate is subjected to image exposure, a light beam corresponding to image data to be recorded on the printing plate is irradiated on the printing plate while the printing plate is mounted to a revolving drum and held thereto as the rotating drum is rotated at a high speed, whereby the printing plate is scanned and exposed.
Among image exposure apparatuses in which a printing plate is exposed to light using a rotating drum, there is an image exposure apparatus that uses a fixing device to fix non-image portions of both ends of the printing plate along the circumferential direction of the rotating drum by clamping the ends of the printing plate to the rotating drum when the printing plate has been mounted to the rotating drum. Such a fixing device generally nips the printing plate ends between clamp portions and the rotating drum by urging the clamp portions facing the printing plate toward the periphery of the rotating drum with an urging force.
However, because a leading edge portion of the printing plate is clamped by a clamp that is continuously fixed to the rotating drum, there has been the need to switch a trailing edge of the printing plate with the leading edge (i.e., reverse the rotating drum) at the time the printing plate is ejected. There has thus been a problem in that switching the rotation of the drum from a normal rotation to a reverse rotation not only requires time, but the interval until the next image is exposed becomes long and working efficiency is poor.
The present invention has been devised in consideration of the facts described above. An object of the present invention is to provide an apparatus and method in which sheet material is subjected to a predetermined processing, and an image recording apparatus, which can improve working efficiency.
This object is achieved in accordance with the principles of the present invention by an apparatus for subjecting sheet material to predetermined processing, the apparatus comprising:
(a) a rotatably mounted drum having a periphery for winding sheet material thereon;
(b) a leading edge clamp unit movable to a withdrawn position separated from the drum and to a clamping position proximate the drum, the leading edge clamp unit including a leading edge chuck for clamping the leading edge of the sheet material to the drum;
(c) a trailing edge clamp unit movable to a withdrawn position separated from the drum and to a clamping position proximate the drum, the trailing edge clamp unit including a trailing edge chuck for clamping the trailing edge of the sheet material to the drum;
(d) a processing element by which sheet material on the periphery of the drum is subjected to predetermined processing;
(e) a wrapping element, that moves in correspondence with a clamp operation of the leading edge chuck, to wrap the sheet material on the periphery of the drum in a sequence of a sheet material front portion, a middle portion and an end portion; and
(f) a separation element, that moves in correspondence with an unclamp operation of the leading edge chuck, to separate the sheet material from the periphery of the drum in a sequence of the sheet material front portion, middle portion and end portion.
The object is also achieved in accordance with the principles of the present invention by a method of subjecting sheet material to predetermined processing, using a rotatable drum having a periphery on which sheet material is wound, the method comprising the steps of:
(a) clamping the sheet material leading edge to the drum;
(b) winding the sheet material on the drum periphery in order of the sheet material front portion, middle portion and end portion;
(c) clamping the sheet material trailing edge to the drum;
(d) subjecting the sheet material on the drum periphery to predetermined processing;
(e) disengaging the clamp on the sheet material leading edge; and
(f) removing the sheet material from the drum periphery in order of the sheet material front portion, middle portion and end portion.
The object is also achieved in accordance with the principles of the present invention by an apparatus for recording an image on a printing plate, the apparatus comprising:
(a) a rotatably mounted drum having a periphery for winding a printing plate thereon;
(b) a leading edge clamp unit movable to a withdrawn position spaced from the drum and to a clamping position proximate the drum, the leading edge clamp unit including a leading edge chuck for clamping the printing plate leading edge to the drum, and a moving mechanism, which when operated, moves the leading edge chuck between the withdrawn and clamping positions;
(c) a trailing edge clamp unit movable to a withdrawn position spaced from the drum and to a clamping position proximate the drum, the trailing edge clamp unit including a trailing edge chuck for clamping the printing plate trailing edge to the drum, and a moving mechanism, which when operated, moves the trailing edge chuck between the withdrawn and clamping positions;
(d) a recording head disposed for recording an image on a printing plate on the drum periphery;
(e) a wrapping element, that moves in correspondence with a clamp operation of the leading edge chuck, to wrap the printing plate on the drum periphery in a sequence of a printing plate front portion, a middle portion and an end portion; and
(f) a separation element, that moves in correspondence with a clamp disengaging movement of the leading edge chuck, to separate the printing plate from the drum periphery in the sequence of the printing plate front portion, middle portion and end portion.